Osmium spectroscopic properties

Bpy complexes, osmium, spectroscopic and magnetic properties, 37 329-330 Bpy polymers, osmium, spectroscopic and magnetic properties, 37 330 Bradyrhizobium japonicum, leghemoglobin in, 46 499-500... 

We have already alluded to the diversity of oxidation states, the dominance of oxo chemistry and the cluster carbonyls. Brief mention should be made too of the tendency of osmium (shared also by ruthenium and, to some extent, rhodium and iridium) to form polymeric species, often with oxo, nitrido or carboxylato bridges. Although it does have some activity in homogeneous catalysis (e.g. of m-hydroxylation, hydroxyamination or animation of alkenes, see p. 558, and occasionally for isomerization or hydrogenation of alkenes, see p. 571), osmium complexes are perhaps too substitution-inert for homogeneous catalysis to become a major feature of the chemistry of the element. The spectroscopic properties of some of the substituted heterocyclic nitrogen-donor complexes may yet make osmium an important element for photodissociation energy research. 

Osmium(II). The unsubstituted complex [Os(terpy)2]Cl2 was made in 1937 by fusion of the ligand with a mixture of K2[OsC1J and osmium metal, and is singularly unreactive towards either acids or alkalis.191 The green chloride gives a red solution. For its redox and spectroscopic properties see below. 

For redox and electron-transfer properties of [Os(bipy)j] + and [Os(phen)3] + see p. 539. Osmium(IIJ). Oxidation of [Os(bipy)3] + with chlorine yields the violet [Os(bipy)3] ion," "" while the red [Os(phen)3] is similarly prepared by oxidation of [Os(phen)3] +.Resolution of [Os(phen3)f + has been achieved by oxidation of Ae corresponding [Os(phen)3] species. Spectroscopic properties. The electronic absorption spectra of [Os(bipy)3] " and of [Os(phen)3] " " have been measured, as have their circular dichroism spectra " "" and also Ae spectra of [Os(4,4 -Me2bipy)3] " The lifetimes of the charge transfer (MLCT) excited states of... 

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